Method for pouring off melt from a tiltable metallurgical vessel and installation for carrying out the method

ABSTRACT

A method for pouring melt from a tiltable vessel into a receiving vessel is characterized for obtaining an optimum and automated pouring process by the combination of the following features:—determining the tilt position of the metallurgic vessel, in which the melt to be poured from the metallurgic vessel exits in the form of a poured stream, —determining the position of the poured stream resulting from the determined tilt position of the metallurgic vessel, bringing into position the receiving vessel for receiving the poured stream from the metallurgic vessel according to the determined tilt position, and after the beginning of the pouring—tracking of the receiving vessel according to the poured stream changing with the changing tilt angle of the metallurgic vessel as a function of the progressing pouring process.

The invention relates to a method for pouring off melt, in particular slag and/or steel melt, from a tiltable metallurgical vessel, in particular a steelworks converter, into a receiving vessel, in particular a ladle or a slag pot, and also to an installation for automatically carrying out the method.

A method of this type is known from WO 03/004198 A2. This involves pouring off steel melt into a receiving vessel brought into position underneath a tap hole of a steelworks converter, allowance being made for numerous parameters relevant to the tapping, such as for example the tilting angle of the steelworks converter, the state of the lining of the tap hole, the state of the lining of the steelworks converter, the volume of the charge, the tapping time, the chemical compositions of the steel and the slag, the temperature of the same, etc., and the tilting angle of the steelworks converter being set in dependence on these parameters. Independently of this, the receiving vessel is located vertically underneath the tap hole of the converter. The levels of the melt bath of the converter and of the receiving vessel are constantly observed.

For pouring off melts into a casting mold, it is known (DE 26 31 015 A1) to set the tilting angle of a tiltable pouring ladle in dependence on the position of the casting mold, the casting stream leaving the mouth of the pouring ladle and always maintaining its position, i.e. its position in space. The casting mold is provided with a melt level measuring device, so that overflowing of the casting mold can be avoided.

A casting machine with an inductively heatable tiltable melt furnace is known from EP 0 240 128 B1, the melt furnace being tiltable and a casting mold which enters the melt and takes up the melt being submersible in the melt, or the tilting angle of the melt furnace being adjustable, for the purpose of keeping the degree of submersion, and consequently the degree of filling, of the casting mold constant, in dependence on the height of the melt bath level.

It is known from DE 35 32 763 A1 to pour off melt from a tiltable pouring ladle into a casting mold brought into position directly in relation to the pouring ladle, the melt bath level in the casting mold being observed and the tilting angle of the pouring ladle being controlled in dependence on it. A casting machine of a similar configuration is known from DE 12 35 520 A1.

The invention addresses the problem of further developing a method of the type described at the beginning to the extent that the pouring off can be carried out in a fully automated manner, a casting stream that changes as the tilting of the metallurgical vessel progresses being transferred optimally into the receiving vessel.

This problem is solved according to the invention by the combination of the following features:

-   -   establishing the tilting position of the metallurgical vessel in         which the melt to be poured off leaves the metallurgical vessel         in the form of a casting stream,     -   determining the position of the casting stream produced by the         established tilting position of the metallurgical vessel,     -   bringing the receiving vessel into position for receiving the         casting stream produced by the metallurgical vessel in         accordance with the established tilting position and, after the         pouring off has begun,     -   adjusting the receiving vessel in accordance with the casting         stream as it changes in dependence on the tilting angle of the         metallurgical vessel, which changes as the pouring off         progresses.

The height of the bath level in the metallurgical vessel can be determined directly or indirectly; directly by means of a bath level measuring device and indirectly by the height of the bath level in the metallurgical vessel being established before establishing the tilting position, by calculation on the basis of the internal volume of the metallurgical vessel and the weight of the melt or the melts, in the latter case the internal volume of the metallurgical vessel preferably being measured by means of a laser scanner before the filling of the metallurgical vessel.

If the measuring of the bath level in the metallurgical vessel is performed by means of a bath level measuring device, the angle between a measuring beam of the measuring device and the bath level and the distance of the bath level from the measuring device are measured.

A method for tapping steel from a steelworks converter is characterized in that, for pouring off steel melt from a steelworks converter, the bath level of the slag melt is ascertained, the tilting position of the metallurgical vessel for pouring off the steel melt being determined with allowance for the bath level of the slag melt in such a way that the bath level of the slag melt for the tilting position of the steelworks converter is at a safe distance from the converter mouth of the steelworks converter when the steel melt is tapped.

The metallurgical vessel is preferably tilted continuously during the pouring off of melt.

If the tilting of the metallurgical vessel is performed very slowly, the metallurgical vessel can also be tilted step by step to avoid overheating of the drive motors.

The individual steps to be carried out when pouring off are expediently carried out in an automated manner with the aid of a computer control, as is the righting of the metallurgical vessel after pouring.

For the adding of an additive into the receiving vessel, an adding chute is provided, and is adjusted in accordance with the casting stream as it changes in dependence on the tilting angle of the metallurgical vessel, which changes as the pouring off progresses, and/or in accordance with the adjusted receiving vessel.

An installation for carrying out the method according to the invention is characterized by the combination of the following features:

-   -   a metallurgical vessel, equipped with a position measuring         device for measuring the tilting angle and an associated control         for tilting the metallurgical vessel,     -   a receiving vessel, which can be made to travel in the direction         of the tilting plane of the metallurgical vessel, with a         position measuring device and an associated control for the         traveling of the receiving vessel,     -   a measuring device for directly or indirectly, preferably         continuously, recording the bath level of the melt in the         metallurgical vessel, and optionally by a     -   device for detecting the end of tapping, the beginning of slag         tapping and residual steel.

For the adding of an additive, an adding chute is provided, and is equipped with a position measuring device for measuring the position and an associated control for positioning the adding chute in dependence on the position of the casting stream and/or the position of the receiving vessel.

If the recording of the bath level is performed indirectly, a weighing device for the receiving vessel is provided.

The invention is explained in more detail below on the basis of an exemplary embodiment, which is represented in the drawing. FIGS. 1 to 4 show in a schematic representation different tilting positions of a steelworks converter during the pouring off of steel melt and the subsequent pouring off of slag melt.

A steelworks converter 1 is fixed in a customary way in a baling ring 2, which baling ring 2 can be tilted by way of two lifting lugs 4, lying diametrically opposite each other and defining a pivot axis 3, in bearings arranged on the foundation, to be precise by means of an electric drive that is not represented any more specifically.

Underneath the steelworks converter 1, a ladle carriage 5 for receiving steel melt 6 in a ladle 7 and furthermore a slag carriage 8 for receiving slag melt 9 in a slag pot 10 can be made to travel in the plane of symmetry/tilting of the steelworks converter 1, to be precise likewise in each case by means of an electric drive.

Provided to the side of the steelworks converter 1, to be precise likewise in the plane of symmetry/tilting, is a melt bath level measuring device 11 provided with a cooling system. This measuring device 11 is aimed at the interior of the steelworks converter 1, and the height 12 of the melt bath level can be determined as soon as the converter mouth 13 of the steelworks converter 1 is directed toward the measuring device 11 during the tilting of the steelworks converter 1, to be precise by measuring the angle 14 between a measuring beam 15 of the measuring device 11 and the bath level 16 and measuring the distance of the bath level 16 from the measuring device 11. The measuring device 11 may, for example, operate by means of a laser beam or else by means of radar.

The tilting position of the steelworks converter 1 can be established by means of a position measuring device that is usually present in steelworks. In the same way, the positions of the receiving vessels that can be made to travel underneath the steelworks converter, that is to say the ladle 7 and the slag pot 10, can also be established by means of customary position measuring devices that are not represented any more specifically. Both the tilt drive of the steelworks converter 1 and the travel drive of the ladle carriage 5 and of the slag carriage 8 are equipped with controls for exact positioning.

Instead of the measuring device 11, the actual bath level 16 in dependence on the tilting angle of the steelworks converter 1 at any one time can also be calculated on the basis of the actual geometry of the converter at the time (meaning here the state of the lining) and the size of the charge. For this, the actual amount of poured-off steel melt 6 at any one time is continuously recorded during the tapping by means of weighing devices for weighing the total weight of the receiving vessels 7. On the basis of the calculated converter content and the given geometry of the converter, the actual bath level 16 at any one time can consequently be calculated.

The automatic pouring-off operation proceeds as follows: it is started by the operator. The steelworks converter 1 is automatically tilted in the direction for pouring off steel melt 6, the actual bath level 16 at any one time being continuously recorded, to be precise by one of the two methods described above, either from the distance of the bath level 16 from the measuring device 11 and the angle 14 that the bath level 16 forms with the measuring beam 15 of the measuring device 11, or by volume and weight measurements.

A maximum possible bath level 16 is dictated by the lowest edge 13′ of the converter mouth 13. A table with the data for the maximum bath level 16 in dependence on the tilting angle of the steelworks converter 1 is stored in the control system and can be adapted installation-specifically in the course of commissioning. In order to avoid melt being tipped out via the converter mouth 13, the maximum possible bath level is reduced by an adjustable value and it is stipulated for the pouring-off control system as a setpoint bath level value. That is to say, in other words, a safe distance of the bath level 16 from the lowest edge 13′ of the converter mouth 13 is maintained.

The actual data obtained at a given time are used to calculate the tilting position of the steelworks converter 1 in which steel melt 6 to be poured off leaves the tap hole 17 in the form of a casting stream 18. This provides a specific position of the casting stream 18, which is produced by the established tilting position and this position instigates the bringing into position of the receiving vessel 7 for receiving the steel melt 6 to be precise under computer control. The steelworks converter 1 is then tilted into the position for beginning tapping (cf. FIG. 1); in the case of the exemplary embodiment represented, the tilting angle is 51°.

For continuous pouring off of the steel melt 6, the steelworks converter 1 is then tilted further under computer control and the receiving vessel, i.e. the ladle 7, is adjusted under computer control in accordance with the changing casting stream 18, the position of the casting stream 18 being calculated in accordance with the tilting angle of the steelworks converter 1, likewise under computer control, to be precise until the pouring off of the steel melt 6 is ended. This is illustrated in FIG. 2 for the case of the exemplary embodiment represented; the tilting angle of the steelworks converter is 96.7°.

At the end of the pouring off of the steel melt 6, the tap hole 17 is closed, for example by a closure device with a closure body, which can be brought from a standby position into a closing position, as described in EP 1 054 068 A2.

The relationship between the tilting angle of the steelworks converter 1 and the position of the casting stream 18 or the position of the ladle carriage 5 is stored as a fixed parameter in the automation system and is adapted installation-specifically.

During the pouring off of the steel melt 6, additive can be introduced into the ladle 7 by means of an adding chute 19 in dependence on the converter tilting angle of the steelworks converter 1 or in dependence on the position of the ladle carriage 5. The position of the adding chute 19 is likewise recorded by means of a continuous position measuring system and automatically positioned in accordance with the position of the receiving vessel 7. The start of adding additives either takes place automatically or is initiated by the operator.

This is followed by the pouring off of the slag melt 9 via the converter mouth 13, to be precise likewise automatically. It is started by the operator, after which the steelworks converter 1 is automatically tilted in the direction of slag tapping. When the position for the beginning of slag tapping is reached (cf. FIG. 3, tilting angle −100°), the steelworks converter 1 is tilted further at minimal speed until slag melt 9 flows via the crucible mouth into the slag pot 10, which has previously been brought into position. During this operation too, the slag carriage 8 is automatically positioned in dependence on the converter tilting angle. The relationship between the tilting angle and the slag carriage 8 is likewise stored as a fixed parameter in the automation system and is likewise adapted installation-specifically. A slag detection system detects the flowing out of the slag melt 9.

From this point in time, the tapping control system takes over the control of the pouring-off operation. The steelworks converter 1 is then tilted further, continuously or step by step, in accordance with the plan stored in the automation system, until residual steel is detected by the slag detection system or the maximum pouring-off tilting angle (cf. FIG. 4, tilting angle −150°) is reached. After reaching the maximum tilting angle or when residual steel is detected, the steelworks converter is automatically righted again. 

1. A method for pouring off at least one of slag or steel melt from a tiltable metallurgical vessel into a receiving vessel, a ladle or a slag pot, the method comprising automatically establishing a tilting position of the metallurgical vessel in which the melt to be poured off leaves the metallurgical vessel through an outlet from the vessel and in the form of a casting stream, automatically determining the position of the casting stream produced by the established tilting position of the metallurgical vessel, automatically bringing the receiving vessel into a position for receiving the casting stream produced by the metallurgical vessel in accordance with the established tilting position and, after the pouring off has begun, automatically adjusting the position of the receiving vessel in accordance with the casting stream as the casting stream changes in dependence on a tilting angle of the metallurgical vessel as the tilting angle changes as the pouring off progresses.
 2. The method as claimed in claim 1, further comprising establishing a height of a bath level of the melt in the metallurgical vessel before establishing the tilting position, by measuring the melt bath level.
 3. The method as claimed in claim 1, further comprising establishing a height of a bath level in the melt in the metallurgical vessel before establishing the tilting position, by calculation of the bath level on the basis of an internal volume of the metallurgical vessel and weight of the melt.
 4. The method as claimed in claim 3, further comprising measuring the internal volume of the metallurgical vessel by a laser scanner before filling of the metallurgical vessel and later filling the vessel with melt to be poured off.
 5. The method as claimed in claim 2, wherein the measuring of the bath level in the metallurgical vessel is performed by a melt bath level measuring device, by measuring the angle between a measuring beam and the bath level and the distance of the bath level from the measuring device.
 6. The method as claimed in claim 1, wherein during pouring off steel melt from a steelworks converter, ascertaining the bath level of the slag melt, determining the tilting position of the metallurgical vessel for pouring off the steel melt with allowance for the bath level of the slag melt for causing the bath level of the slag melt, for a tilting position of the steelworks converter, to be at a safe distance from a converter mouth of the steelworks converter when the steel melt is tapped.
 7. The method as claimed in claim 6, comprising tilting the metallurgical vessel continuously during the pouring off of melt.
 8. The method as claimed in claim 7, comprising tilting the metallurgical vessel step by step during the pouring off of melt.
 9. The method as claimed in claim 6, further comprising, performing the method in an automated manner with the aid of a computer control.
 10. The method as claimed in claim 1, further comprising introducing an additive into the receiving vessel by means of an adding chute, adjusting the adding chute in accordance with the casting stream as the stream changes in dependence on the tilting angle of the metallurgical vessel, and the tilting changes as the pouring off progresses, and/or in accordance with the adjusted receiving vessel.
 11. An installation for pouring off at least one of slag or steel melt, comprising: a metallurgical vessel for holding the at least one of slag or steel melt to be poured from the metallurgical vessel; a first position measuring device operable for measuring the tilting angle of the metallurgical vessel, and an associated control for tilting the metallurgical vessel to a measured extent, including to pour the slag or steel melt, a receiving vessel, which is movable relative to the metallurgical vessel in a direction of a tilting plane of the metallurgical vessel to be moved to a position to receive the slag or steel melt being poured from the metallurgical vessel; a second position measuring device for measuring the position of the receiving vessel device and an associated control for controlling the travel of the receiving vessel to enable receiving the slag or steel melt being poured as the metallurgical vessel is tilted to various tilt angles wherein the controls cooperate to tilt the metallurgical vessel and move the receiving vessel so that poured slag or steel melt will be received in the receiving vessel; a measuring device for directly or indirectly, recording a bath level of the melt in the metallurgical vessel and operative on the control of the metallurgical vessel for affecting the tilting angle thereof, and optionally by a device for detecting the end of tapping, the beginning of slag tapping and residual steel and the detecting device is also operative on the control of the metallurgical vessel for affecting the tilting angle thereof.
 12. The installation as claimed in claim 11, further comprising an adding chute positioned and operable for adding an additive into the receiving vessel, a third position measuring device operable for measuring the position of the chute and an associated control for positioning the adding chute in dependence on the position of at least one of the casting stream from the metallurgical vessel and/or the position of the receiving vessel.
 13. The installation as claimed in claim 11, further comprising a weighing device for the receiving vessel and operative on the control of the metallurgical vessel for affecting the tilting angle thereof. 